Recently, a new class of thermoelastic sulfonated polymers has been described in a number of U.S. Patents. These sulfonated polymers are derived from polymeric materials having olefinic unsaturation, especially elastomeric polymers such as Butyl and EPDM rubbers. U.S. Pat. No. 3,642,728, herein incorporated by reference, clearly teaches a method of selective sulfonation of olefinic unsaturation sites of an elastomeric polymer to form an acid form of a sulfonated elastomeric polymer. The olefinic sites of the elastomeric polymer are sulfonated by means of a complex of a sulfur trioxide donor and a Lewis base. The SO.sub.3 H groups of the sulfonated elastomer can be readily neutralized with a basic material to form an ionically cross-linked elastomer at room temperature. However, these ionically cross-linked elastomers may be processed like a conventional thermoplastic at elevated temperatures under a shear force in the presence of selected preferential plasticizers, which dissipate the ionic associations at the elevated temperatures, thereby creating a reprocessable elastomer.
The basic materials used as neutralizing agents are selected from organic amines or basic materials selected from Groups I, II, III, IV, V, VI-B and VIII, and mixtures thereof, of the Periodic Table of Elements.
U.S. Pat. No. 3,836,511, herein incorporated by reference, teaches an improved process for the sulfonation of the olefinic sites of the elastomeric polymer, wherein the improved sulfonating agent is selected from acetyl sulfate, propionyl sulfate and butyryl sulfate. The neutralizing agents employed to neutralize the acid form of the sulfonated elastomeric polymers are organic amines.
This class of sulfonated polymers is especially interesting because at low levels of sulfonate groups, the polymers are readily soluble in a variety of hydrocarbon fluids, such as oils, jet fuel, gasoline and the like, provided that the polymer backbone is suitably soluble in such fluids. For example, EPDM, or ethylene-propylene-diene monomer terpolymer is soluble in oil. The sulfonated version of this polymer, Sulfo-EPDM is also soluble in oils at low sulfonate content, however, at higher sulfonate content the aggregation of the ionic groups can lead to a gel phase of the ionic polymer. The instant invention is based on the concept that an amine terminated poly .epsilon.-caprolactone can interact with the associated ionic groups and thereby create a more soluble species: a polymer complex of the sulfonated polymer and the polycaprolactone. This complex (or acid-base adduct if the amine is interacted with the polymer sulfonic acid) can now be soluble in a variety of hydrocarbon fluids and due to the specific structures of these systems, we find they are very effective in inhibiting the tendency of certain paraffinic fluids to solidify at low temperatures. Thus, these systems are good flow modifiers.
With the increase in the use of hydrocarbon fuels of all kinds, a serious problem has arisen in areas frequently subjected to low temperatures in the cold test characteristics with heating oils and diesel and jet fuels that have too high a pour point, resulting either in distributional or operating difficulties or both. For example, the distribution of heating oils by pumping or syphoning is rendered difficult or impossible at temperatures around or below the pour point of the oil. Furthermore, the flow of the oil at such temperatures through the filters cannot be maintained, leading to the failure of the equipment to operate.
Also the low temperature properties of petroleum distillate fuels boiling in the range between about 140.degree. C. and about 400.degree. C. have attracted increasing attention in recent years because of the growth of a market for such fuels in subarctic areas and because of the development of turbo-jet aircraft capable of operating at altitudes where temperatures of -50.degree. C. or lower may be encountered.
It is, of course, well known to add pour depressants to lubricating oils to lower the pour point. These lube oil additives, mostly high molecular weight organic compositions formed by alkylation of benzene or naphthalene or derivatives thereof, or by polymerization of lower molecular weight methacrylates, or by condensation polymerization of various kinds, are not satisfactory in service with middle distillate and lighter fuels.
A wide variety of compounds have been found to be effective as pour point depressants for lubricating oil. Among the best known are "Paraflow", "Santopour", and "Acryloid" and their modifications. They are prepared either by condensing aromatic compounds with long chain paraffins, such as wax, or by condensing olefinic esters. It is generally considered that these pour depressants are effective in that upon cooling an additive containing oil, the hydrocarbon chain of the additive becomes incorporated into the crystal lattice of the separated wax, while the other part of the pour depressant molecule prevents the crystals from adhering together to form a gel structure. The failure of these additives to be effective in middle distillates may at least in part be due to the basic difference in the composition between the wax in lubricating oils and that in middle distillate fuels.
The concept of this invention is the use of hydrocarbon soluble or dispersible polymers based on poly-caprolactone (PCL) as pour point depressants and middle distillate flow improvers. Specifically these polymers are prepared by polymerization of -caprolactone initiated by a suitable diamine (of U.S. Pat. No. 4,379,914). The resultant lactone polymers are not typically soluble in paraffinic hydrocarbons. We have found that soluble systems comprising these polymers can be prepared in several ways:
(1) Neutralization of a polymer sulfonic acid with the amine terminated PCL such as Sulfo EPDM, as covered in U.S. Pat. No. 4,379,914 issued 4/12/83. PA0 (2) Interaction of the amine terminated PCL with a suitable metal neutralized Sulfonated polymer such as zinc sulfonated EPDM. We find that these complexes are especially suited for the instant invention, especially those employing the zinc counter ion. The latter class of materials is especially effective as wax crystal modifiers.